Metal-hydride-actuated electrical relay



J1me 1955 J. E. LINDBERG, JR 3,257,529

METALHYDRIDEACTUATED ELECTRICAL RELAY Filed March 27, 1963 3 Sheets-Sheet I emf INVEN TOR.

JOHN E. [la/0352a, JR 8Y6) s June 21, 1966 J, UNDBERG, JR 3,257,529

METAL-HYDRIBE-ACTUATED ELECTRICAL RELAY Filed March 27, 1963 5 Sheets-Sheet 3 FIG. 6

JNVENTOR. JOHN E LIA/DEERE, JR.

Fla. 8

United States Patent 3,257,529 METAL-HYDRIDE-ACTUATED ELECTRICAL RELAY John E. Lindberg, Jr., Alamo, Calif.

(1211 Upper Happy Valley Road, Lafayette, Calif.) Filed Mar. 27, 1963, Ser. No. 268,378 18 Claims. (Cl. 200140) This invention relates to improvements in electrical relays. This application is a continuation-in-part of application Serial Number 29,397, filed May 16, 1960, now abandoned.

Conventional electrical relays are not able to operate properly when they are in an environment where the temperature is high, e.g., 500 F. or 1000 F. Such heat destroys the insulation and contaminates the contacts and either destroys the relay, renders it inoperative, actuates it at times when it should not be actuated, or causes other troubles. Conventional relays also tend to be affected by changes in pressure, by mechanical vibration, and by external magnetic fields.

Another difficulty with conventional relays is that they tend to be rather large for applications requiring real miniaturization, and if they are miniaturized, they tend to be less reliable than they are normally. Also, con ventional relays produce magnetic fields that, in some installations, interfere with adjacent electrical circuits.

An important object of this invention is to provide an electrical relay of exceptionally small size which is able to give dependable operation under a wide variety of environmental conditions.

Another object of the invention is to provide a relay which can operate at very high temperatures, far beyond those at which conventional relays can function reliably.

A further object of the invention is to provide a relay which operate satisfactorily despite wide changes in external pressure.

Another object of the invention is to provide a relay which is singularly unaffected by mechanical vibration and so solves a problem that has heretofore plagued relay designers.

Still another object is to provide a relay that neither is allected by external magnetic fields, nor produces any significant magnetic fields of its own that may interfere with adjacent electrical circuits.

Yet another object is to provide a time-delay relay in which the delay time can easily be adjusted and is continuously variable over the adjustment range.

Other objects and advantages will appear from the following description of several preferred embodiments of this invention.

In the drawings:

FIG. 1 is an enlarged view in elevation and in section of a single-pole, single-throw relay embodying the principles of this invention.

FIG. 2 is a similar view of another type of single-pole, single throw relay also embodying the principles of this invention.

FIG. 3 is a similar view of a single-pole, double-throw relay, embodying another modified form of this invention.

FIG. 4 is a similar view of a double-pole, single-throw relay, embodying still another modified form of this invention.

FIG. 5 is a similar view of yet another modified form of the invention, namely a single-pole, double-throw, balance-type relay, suitable for use in bridge circuits.

FIG. 6 is a greatly enlarged view in elevation and in section of another modified form of the invention comprising a single-pole, single-throw relay.

FIG. 7 is a plan view in section of the relay of FIG. 6, taken along the line 77.

Patented June 21, 1966 FIG. 8 is a fragmentary view in elevation and in section of a portion of a relay like those of FIGS. 15, showing a modified form of heating arrangement.

FIG. 9 is a similar view of an additional form of heating arrangement.

My new relay has several important differences from prior art relays. One is that it operates by the input electricity heating a metallic hydride, the emission of hydrogen actuating a hightemperature pressure switch; another is that only high-temperature ceramic is used for insulation; another is that it utilizes a high temperature metal such as molybdenum or an alloy thereof, for some or all of the metal parts and particularly for a snap-action diaphragm.

The metallic hydrides used are those that reversibly ingas and outgas hydrogen with consistency. Not all hydrides will do this. Moreover, there are two types of hydrides that can be used. A first type outgasses when heated and ingasses when cooled; a second type (within a certain temperature range at least) outgasses when cooled and ingasses when heated.

In all instances, the hydrides employed in this invention are those which have a trigger-type action. In other words, a hydride of the first type outgasses very little or no hydrogen until a certain threshofii temperature is reached, and then it outgasses large amounts of hydrogen. These hydrides thus differ basically from activated carbon which outgasses at low temperatures and does so gradually, but is exhausted at relatively low temperatures, subsequent increase in pressure being due only to the gas itself. The hydrides used in the relays of this invention are quite inactive at temperatures below their threshold temperature and are then quite responsive and active. Therefore, they do not respond to environmental temperatures below their threshold but react quickly when it is intended that they should.

As said, the first type of metallic hydride useful with this invention retains gas at temperatures below a threshold but releases hydrogen gas when heated above the threshold. Upon cooling it again takes up the gas and tends to return to its original state. Among the materials of this first type are the alkaline and alkaline earth hydrides and the hydrides of certain other metals, and some borohydrides. As I shall point out later, hydrogen is an especially useful gas when applied to this invention. It combines with or dissolves in the following metals to form a hydride of this type: lithium, sodium, potassium, rubidium, cesium, calcium, strontium, barium, titanium, vanadium, ytterbium, zirconium, niobium, hafnium, tantalum, palladium, the rare earth metals (atomic numbers 57 through 71 and the actinide metals (atomic numbers 89 through 103). Of these, the actinides are, in most instances, undesirable, and most rare earth metals are very expensive. The sodium and calcium groups are very reactive with air or moisture and so tend to cause trouble if the relay should get broken. Hence, I prefer to use the hydrides of zirconium, titanium, vanadium, tantalum, palladium, niobium and similar ones, including the less expensive of the rare earth metals.

The capacities of these materials of the first type for taking up and releasing hydrogen vary widely from one element to another; for example, titanium absorbs 335 cc. of hydrogen per gram at 600 C. while vanadium absorbs 10 cc. per gram at the same temperature. But in all instances, they trigger and do so at relatively high temperatures, to emit large quantities of gas.

The hydrides of the second type also take up and release gas reversibly, but they take up gas when heated and release it again when cooled. Among these materials are platinum, rhenium, osmium, iridium, ruthenium, and rhodium. As a rule, the materials of the second type take up and release less hydrogen than do the materials of the first type of hydride, given equal weights of both. Other hydrides of this type which emit or take up very little hydrogen are not even included in this invention.

The basic procedure of this invention is as follows: A quantity of metal hydride, which may be one or a mixture of severeal of the above-mentioned materials, is placed in a closed container of a type able to withstand high temperatures (along with a suitable supply of gas, if desired, as in the second type of hydride). The container is so constructed that its volume is an increasing function of its internal pressure, that is, an increase in its internal pressure causes some part of it to move outward. Preferably, the outwardly moving part is a snap acting diaphragm. Thus, when the hydride within the container is heated or cooled, the movable part of the container is displaced, and the displacement is used to open or close an electrical contact. The broad term relay is thus applied to devices utilizing the principles of this invention. Examples now will be given.

FIG. 1 shows a single-pole, single-throw relay in which a flexible metal diaphragm 21 is sandwiched between two plates 22 and 23 of metal or other non-porous high-temperature material. All the materials in the relay must be able to Withstand high temperatures and to do so without reacting deleteriously with hydrogen. Molybdenum and its alloys are preferred metals. The diaphragm 21 has a circular blister 24, preferably of spherical shape, the convex side of which extends into a cavity 25 in the plate 23. The concave side of the blister 24 faces a surface 26 of the plate 22 forming part of a chamber 27. The plates 22 and 23 are joined to the diaphragm 21 in such a way that the chambers 25 and 27 are airtight. Commercial molybdenum and its alloys are able to retain their snap-action ability at quite high tempera tures and in the presence of hydrogen.

Into an opening 28 in the chamber 25 is sealed an open end 29 of a tube 30, whose other end 31 is sealed airtight. The tube is made of a suitable non-porous high temperature insulating ceramic such as quartz or aluminum oxide or beryllium oxide, and contains a quantity of the metal hydride 32 discussed above, such as zirconium hydride. Imbedded in the transducing agent 32 is a high-temperature wire filament 33 of a type that does not react with the hydride, such as molybdenum, tungsten, or platinum whose ends 34 and 35 are brought through the wall of the tube 30 by means of airtight ceramic or high-temperature metal bushings 36 and 37. A porous high temperature plug 38 set in the end 29 of the tube 30 prevents any of the hydride 32 from getting into the chamber 25, While enabling easy flow of gas back and forth between the chamber 25 and the tube 30. Since the chamber 25 is on the same side of the diaphragm 21 as the hydride 32, which is a transducing agent, it may be called a transducer chamber," and the chamber 27 may be called the anti-transducer chamber.

The plate 22 has an opening 39 leading into the chamber 27, into which is sealed a second high-temperature ceramic insulating tube 40 having an end 41 leading into the chamber 27. The other end 42 of the tube 40 is sealed airtight by means of a high temperature metal cap 43. A high-temperature metal contact-member 44, such as molybdenum is fastened at one end 45 to the cap 43 and extends along the axis of the tube 40. The other end 46 of the member 44 protrudes slightly below the surface 26 of the plate 22 into the chamber 27. Provision is made for attaching a Wire 47 to the cap 43 and a wire 48 to the metal diaphragm 21.

The operation of the relay 20 is as follows: Normally the blister 24 of the diaphragm 21 is out of contact with the end 46 of the contact-member 24, so that no electrical continuity exists through the relay 20 between the wires 47 and 48. However, if a source 50 of electrical current is connected across the wires 34 and 35 and the filament circuit closed, as by throwing a switch 51, current will flow through the filament 33, causing it to heat itself and the surrounding hydride; the temperature rises rapidly and (often in a fraction of a second, but slower if desired), soon exceeds the threshold temperature, causing the hydride 32 to release hydrogen gas. This gas diffuses through the porous plug 38 into the chamber 25, raising the pressure there, and when sufficient gas is evolved (which may be in a fraction of a second) the pressure in the chamber 25 will be raised enough to cause the blister 24 of the flexible metal diaphragm 21 to be deflected against the end 46 of the contact-member 44, completing the connection between the wires 47 and 48. When the switch 51 is opened, the source 50 of E.M.F. is disconnected from between the wires 34 and 35, the current through the filament 33 ceases, and the hydride 32 begins to cool. As it cools, it takes up the gas which it has evolved, thus reducing the pressure in the chamber 25, and the blister 24 springs back to its normal shape, breaking the electrical connection between the wires 47 and 48.

Notice that in its deflected position the blister 24 rests against an essentially flat surface, the surface 26 of the plate 22, since the end 46 of the contact-member 24 is relatively small in area and protrudes only slightly beyond the surface 26. Thus the deflection of the blister 24 is limited, and permanent deformation of the diaphragm 21 is prevented.

The quantity of current through the filament 33, necessary to bring about deflection of the blister 24, may be varied in a number of ways. A stiffer diaphragm 21 normally requires a higher pressure in the chamber 25 for deflection. This higher pressure may be secured by heating the transducing agent 32 to a higher temperature. But greater heating of the transducing agent requires more current through the filament 33. Therefore, a stiffer diaphragm 21 tends to reduce the amount of current through the filament 33 necessary to actuate the relay 20, while a weaker diaphragm 21 tends to reduce the amount of current necessary. Different hydrides 32 require different temperatures for maintaining a given equilibrium pressure in a closed volume. Therefore, the kind of hydride used influences the magnitude of the actuating current, as do the relative volumes of the tube 30 and the chamber 25, and the rate of conduction of heat away from the hydride 32.

Several means are available for controlling the stiffness of the diaphragm 21: (1) as the ratio of the diameter of the blister 24 to its height decreases, the diaphragm 21 becomes stiffer and requires greater pressure for defiection; (2) a thicker diaphragm is stiffer than a thin one of the same material; (3) some materials produce stiffer diaphragms than others; (4) apart from these design factors, the eflective stiffness of the diaphragm 21 may be controlled in a simple and adjustable way by varying the pressure in the chamber 27 on the concave side of the blister 24. The greater the pressure in the chamber 27, the greater the pressure necessary to deflect the blister 24. Since the pressure in the chamber 27 can be controlled easily during the manufacture of the relay 20, the current necessary for actuation, that is, the sensitivity of the relay, also can be controlled easily. The pressure in this chamber 27 may also be used to keep the operating characteristics of the diaphragm 23 constant when the ambient temperature changes, or to vary it if desired.

If the relay of FIG. I is called upon to break considerable current flowing through the wires 47 and 48, additional considerations enter into the design of the diaphragm 21 and the contact-member 44. The area of contact between the diaphragm 21 and the contact end 46 is made sufficiently large to present negligible resistance to the current flow, so that a large potential drop across the relay 20 and heating of the relay do not occur. In addition, it is undesirable for the blister 24 to spend much time near but not touching the end 46, as it would if the position of the blister 24 were a slowly-varying function of the pressure on its convex side; for then an arc would occur with each operation of the relay 20, and arcing eventually will pit and deform the contacting surfaces of the diaphragm 21 and end 46. Therefore, the blister 24 preferably is designed to exhibit snapaction; that is, it remains essentially undeforrned until the pressure in the chamber 25 reaches a certain critical value, at which point the blister 24 snaps over against the end 46. Fairly narrow limits restrict the design of the blister which will exhibit the proper snap-action. For example a %-inch diameter blister in a 0.002-inch thick molybdenum diaphragm will have good snap-action when its height is between 0.004 and 0.006 inch.

The form of the hydride 32 in the relay is not highly critical, although it can have a significant effect on the operation of the relay. Preferred forms are finely granulated, perhaps 200 mesh, or pelleted, with pellets about SO-mesh size. However the hydride 32 also can be in the form of slender rods or tubes placed in the region of the filament 33, or it can be powder compressed into a porous cake of appropriate size to place in the tube 30. Some of these forms are discussed in detail in my application Serial No. 759,717, now abandoned. In any event, the form of the hydride 32 is such that gas can flow freely between its parts.

The relay 20, when used with zirconium hydride or with others of the first type, has normally-open contacts; that is, when no current flows through the filament 33, the blister 24 is not in contact with the end 46. If, however, the second type of hydride is used in the tube 30, the relay 20 may be operated as a normally-closed relay. In this case, an hydride forming metal 32, such as powdered rhodium, is placed in an atmosphere of gas (e.g., hydrogen) in the tube 30 at normal temperatures, and the gas pressure in the chamber is adjusted so that the blister 24 is firmly in contact with the end 46. When current flows through the filament 33 and heats up the rhodium 32, the metal 32 takes up gas and reduces the pressure in the chamber 25 until the blister 24 is flexed away from the end 46. When the filament current is stopped, the rhodium hydride 32 cools and releases the gas which it has taken up, thus increasing the pressure in the chamber 25 and deflecting the blister 24 against the end 46.

FIG. 2 shows a modified form of relay 60 of this invention. Again, there is a metal diaphragm 61 sandwiched between two plates 62 and 63. A blister 64 normally lies in a cavity 65, into which opens a tube 66 containing a transducing agent 67, preferably a hydride of the first type, such as vandium hydride, for a normally closed relay 60. A heating coil 68 heats the hydride 67 when a switch 69 is closed. A chamber 70 of suitable size is provided on the opposite side of the blister 64. In the relay 60 a contact 71 lies on the convex side of the blister 64 instead of the concave side, as in FIG. 1; hence the contact 71 and the hydride 67 both are on the same side of the diaphragm 61 instead of on opposite sides. A wire 72 is connected to the contact 71, while a wire 73 is connected to the diaphragm 61. Again, high temperature materials are used throughout.

With a hydride 67 such as vanadium hydride or zirconium hydride in the tube 66, the relay 60 is normally closed. When the filament 68 is heated, the gas evolved increases the pressure in the chamber 65 and deflects the blister 64 away from the contact 71, reaking the connection between the wires 72 and 73. When the filament current is shutoff, the hydride 67 cools and takes up the gas it has released, reducing the pressure in the chamber 65 so that the blister 64 returns to its normal position, resting against the contact 71.

Notice that the sensitivity of the relay 60 may be controlled just as may that of the relay 20, by adjusting the pressure in the chamber 70 on the concave side of the blister 64. Notice also that the surface 74 of the plate 62 limits the amount of deflection of the blister 64, just as corresponding members did in the relay 20. If a hydride 67 like rhodium hydride is used in the relay 60, it may be operated as a normally-open relay.

FIG. 3 shows another modified form of this invention; a single-pole, double-throw relay partaking of the nature of both the relays 20 and 60. Its diaphragm 81 has a blister 82 that normally rests on a contuct-rnember 83 lying on the same side as a container 84 for a hydride type of transducing agent 85. However, when a filament 86 beats the agent 85, the resulting emission of gas forces the blister 82 away from the contact-member 83 and against a contact-member 87 that lies in a chamber 88 on the opposite side of the diaphragm 81 from the transducing agent 85. A wire 90 is secured to the diaphragm 81, while a wire 91 is electrically connected to the contact member 83 via a cap 92. Similarly, a wire 93 is electrioa lly connected to the contact-member 87 through a cap 94.

When the hydride releases gas and the increased pressure deflects the blister 82 away from the contactmember 83 and against the contact-member 87, the connection between the wires and 91 is broken and connection is made between the wires 90 and 93. When the de-hydrided metal 85 takes up the gas which it has released, the blister 82 returns to its rest position against the contact 83, remaking the connection between the wires 90 and 91 and breaking the connection between the wires 90 and 93. Depending upon the type of hydride, the connection between the wires 90 and 91 can be made, respectively, normally-closed or normally-open, as desired.

FIG. 4 shows still another form of this invention. It is a double-pole, single-throw relay having two diaphragms 101 and 102 with respective blisters 103 and 104, on whose concave sides are separate airtight chambers 105 and 106. Each blister 103, 104 has a respective contact-member 107, 108, each secured to a cap and 111, and a separate wire 112, 113 attached to each cap 110, 111. A wire 114 is attached to the diaphragm 101 and a Wire 115 to the diaphragm 102. The two diaphragm-contact assemblies are electrically independent so that the relay 100 can control two separate circuits simultaneously.

When a hydride transducing agent 116 releases gas into a chamber 117 on the opposite side of the diaphragms 101 and 102 from the contact-members 107 and 108, the increased pressure in the chamber 117 tends to deflect both blisters 101 and 102 against their respective contacts 107 and 108, making separate connections between the wires 112 and 114 and the wires 113 and 115. When the transducing agent 116 takes up the gas which it has released, the pressure in the chamber 117 drops, and the blisters 101 and 102 return to their relaxed positions, breaking the connections between the wires 112 and 114 and the wires 113 and 115.

In FIG. 5 is shown. another form of this invention, a polar relay 120; that is, one that responds to the difference between two signals rather than to one signal. The relay 120 has two supplies of hydride-type transducing agent, 121 and 122. Its diaphragm 123 need not have a blister. If the blister is omitted, the deflection of the diaphragm 123 will be gradual rather than sudden.

Here, then, are two contact-members 124 and 125, on opposite sides of the diaphragm 123, and connected to wires 126 and 127. A Wire 128 is connected to the diaphragm 123. Wires 130 and 131 are connected to a source 132 of electric current and to a filament 133 in the transducing agent 121, while wires 134 and 135 are connected to another source 136 of electric current and to a filament 137 in the transducing agent 122.

Using a transducing agent of the first type, such as titanium hydride, in both instances, the operation of the relay 120 is as :follows. If the relative currents through the two filaments 133 and 137 are such that the pressures in their respective chambers 138 and 139 are equal, then the diaphragm 123 remains undefiected and midway between the contacts 124 and 125. If, however, the current through the filament 133 increases relative to that through the filament 137 (or, equivalently, if the current through filament 133), then the transducing agent 121 releases gas (or the transducing agent 122 takes up gas) with the result that the pressure in the chamber 138 becomes greater than that in the chamber 139. This pressure difterence deflects the diaphragm 123 against the contact 125 completing the connection between the wires 127 and 128. Similarly, if the current through the filament 133 decreases relative to that through the filament 137, then the diaphragm 123 is deflected away from the contact 125 and against the contact 124, breaking the connection between the wires 127 and 128 and completing the connection between the wires 128 and 126.

The actuation of the relay 120 does not depend directly upon the magnitude of the current flowing through either of the filaments 1133 and 137, but rather on their value relative to each other. If a relay is constructed so that the diaphragm 123 is midway between the contacts 124 and 125 when the currents through the two filaments 133 and 137 are equal, then the diaphragm 123 does not make contact with either of the contacts 124 and 125 even though the currents through the filaments 133 and 137 are varied over a wide range but maintained always equal. Alternatively, the relay 120 can be constructed so that the diaphragm 123 remains midway between the contacts 124 and 125 when the ratio of the currents through the filamerits 133 and 137 maintains a certain value, in which case the currents through the filaments i133 and 137 may be varied over a considerable range, keeping their ratio constant, and the diaphragm 123 will not touch either of the contacts 124 and 125.

Platinum or ruthenium hydrides or others like them (of the second type) may be used in the relay 120 without altering its basic mode of operation. The design of the two filaments 133 and 137, as well as the relative volumes of the chambers 138 and 139, also may be changed in order to secure the desired operation of the relay without departing from the principles just described.

A useful design variation in the relay 120 is to form a suitable dimple or blister (see FIGS. 1-4) in the diaphragm 123 in the area where it separates the chambers 138 and 139, in order to secure snap-action in its movement. With such a design, the diaphragm 123 remains in contact with one of the contacts 124 or 125 until a change in the relative pressures in the chambers i138 and 139 produces sufficient force on the diaphragm 123 to snap it over against the other contact. The diaphragm 123 then remains against the latter contact until a subsequent pressure change snaps it back against the first contact. Thus, there is no prolonged period during which there is a connection between neither the wires 127 and 128 nor the wires 128 and 126.

The relays of FIGS. 1 through utilize single or multiple diaphragms, contacts, or supplies of transducing agent. Clearly, these various arrangements may be combined in many ways to form complex relays capable of performing intricate and diverse functions. There is virtually no limit, for example, to the number of separate diaphragms which may be actuated by a single supply of hydride type transducing agent, or to the number of supplies of hydride type transducing agent which may actuate a single diaphragm. However, no such combination or complication departs from the basic principles of this invention, nor from the basic designs illustrated in FIGS. 1 through 5.

FIGS. 6 and 7 show a modified form of relay 150 which can be made very small and flat. The relay 150 includes a high temperature metal diaphragm 151 having a dimple or blister 152 to which a suitable lead-wire 153 is connected. The diaphragm 1 is held between two plates 154 and 155 of insulating ceramic suitable for high-temperature use. Sealed to the plate 155 is a high-temperature metal contact button 156 to which a suitable wire 157 is externally attached. The circuit between the wires 153 and 157 is closed when the blister 152 is forced against the button 156; otherwise, the circuit is open.

The plate 154 has a recess 160 to accommodate the blister 152 and to provide sufiicient area for a chamber 161 on the opposite side of the diaphragm 151 from the button 156 and a chamber 162 on the same side as the button 156. The plate 154 may be bored to provide one or more holes 163 leading from the chamber 161 to the opposite side of the plate 154, where there is a fiat face 164. On the face 164 is printed or otherwise applied a thin electrical resistance member 165, which comprises the heating filament for this embodiment of the invention. On top of the filament 165 is applied a thin layer of a suitable hydride 166, such as zirconium hydride or tita-.

nium hydride. On top of this, leaving sulficientspace to assure gas flow, is sealed a cover plate or member 167 which may be a recessed ceramic plate like the plates 154 and 155, with a recess 168, or may be another form of closure member. The important thing is simply to give any gas released from the hydride 166 access to the holes 163 while sealing the members 154 and 167 airtight.

Operation of the transducer 150 is obviously the same in substance as that of the transducer 20. In other words, when the filament 165 is heated, the transducing agent 166 releases gas (or takes it up if it is of the second type, like rhenium hydride). transducing agent 165, it passes through the opening 163 into the chamber 161 and forces the blister 152 against the button 156, actuating the relay 150. This entire relay 150 may be made smaller than an inch square and a quarter of an inch thick.

FIGS. 8 and 9 show some alternative ways of heating the hydride. They exemplify the fact that direct filamentary heating is not necessary. In fact, the transducing agent can be heated by a flame where electrical heating is not desired, but for a purely electrical relay, there are these alternatives. The structure shown in FIG. 8 includes a pair of electrodes 170 and 171 positioned at opposite ends of a hydride-type transducing material 172 with a gap between them. Leads 173 and 174 connect them through switch 175 to a source 176 of high-voltage current. When the high-voltage is applied, arcing takes place across the electrodes 170 and 171 giving a very quick heating of the transducing agent [72 and rapid gas emission.

FIG. 9 shows another form of heater, comprising a closed coil 180. The coil 180 is embedded in a transducing agent 181 and is excited by a radio-frequency field outside the relay, suitable material being used to form the tube 182 that contains the agent 181 so that there is no undesired shielding effect.

From the foregoing descriptions it will be apparent that very small relays may be made and that they will be dependable. External pressures over a wide range produce no effect on their operation since all contact members are within sealed chambers. Vibration has no effect except possibly in some unusualy extreme instance, and even then by proper use of materials, the effect can be eliminated. External magnetic fields have no effect, except as they may be purposely used with induction heating as in FIG. 9, so long as the diaphragm itself is non-magnetic, as are molybdenum and Kovar, two of the preferred materials for this purpose, and the magnetic field produced by the filament can be made negligible.

For normal relay operation, it is desirable that the relay respond instantly upon application of the actuating current. However, some situations require that the relay not respond until a certain fixed time after application of the actuating current.

From the foregoing discussion it may be seen that a relay utilizing the principles of this invention will respond only when the temperature of its transducing agent reaches a critical value. While instantaneous response When gas is released from the can be attained by applying strong heating to a small mass of transducing agent, nevertheless, if desired, a fixed delay can be introduced by heating the transducing agent slowly. The length of the time delay can easily be controlled by adjusting the magnitude of the actuating current: the stronger the current, the more rapid the heating of the transducing agent and the shorter the time delay. Clearly a time lag could easily be introduced into the response of any of the above-mentioned forms of this invention merely by reducing the actuating current. All of the factors previously mentioned as affecting the sensitivity of these relays also will affect the time delay characteristics. While high environmental temperatures can affect the hydride transducing agent, the hydride may be chosen to avoid the effect or minimize it. Temperatures up to 2000 F. need have no effect on the actuation of the diaphragm. By choosing the right material for the right job according to the principles given here and in my referred-to copending application, the relay may be used at temperatures far above those where prior-art relays can be used, and the operation will be consistent and dependable.

To those skilled in the art to which this invention relates, many changes in construction and Widely differing embodiments and applications of the invention will suggest themselves without departing from the spirit and scope of the invention. The disclosures and the description herein are purely illustrative and are not intended to be in any sense limiting.

I claim:

1. An electrical relay suitable for use in environments subjected to high temperatures comprising a high-temperature-resistant enclosure; metallic hydride in said enclosure having a threshold temperature above the temperatures to which the environment is subject; electrical means in heat conducting relationship with said hydride for primarily heating said hydride above said threshold temperature; a snap-action electrically conductive diaphragm of metal whose ability to snapact is not greatly affected by high temperature closing an area of said enclosure and deflected by variation in pressure; and an electrical contact in said enclosure of high-temperature-resistant metal against which said diaphragm is snapped under some pressure conditions and away from which it is moved under other pressure conditions.

2. An electrical relay comprising a hydride from the group consisting of zirconium, titanium, vanadium, niobium, tantalum, and palladium; electrical heating means for said hydride; a molybdenum snap-action diaphragm; a high-temperature-resistant housing divided by said diaphragm into two sealed airtight chambers, namely, a transducer chamber containing said hydride and the gas emitted therefrom and an anti-transducer chamber; and an electrical circuit connected to said diaphragm and having a molybdenum contact member in said anti-transducer chamber, against which said diaphragm is movable under pressure, whereby said diaphragm and said contact member act as a switch actuated by gas released from said hydride.

3. The relay of claim 2 wherein said anti-transducer chamber is pre-pressurized.

4. An electrical relay comprising a metallic hydride of the type that releases large quantities of gas when heated; electrical heating means primarily for said hydride; an electrically conductive diaphragm of a metal that retains its strength and springiness well at high ternperatures and which does not then react with hydrogen to a deleterious degree; a housing of high-heat-resistant material divided by said diaphragm into two sealed airtight chambers, namely, a transducer chamber containing said hydride and the gas emitted therefrom and an antitransducer chamber; and an electrical circuit connected to said diaphragm and having a contact member of highheat-resistant metal, also resistant to hydrogen, in said transducer chamber, against which said diaphragm normally rests and from which said diaphragm is movable under pressure, whereby said diaphragm and said contact member act as a switch actuated by gas released from said hydride.

5. The system of claim 4 wherein said anti-transducer chamber is pffi-ptCSSllTiZECl.

6. An electrical relay capable of use in an environment subject to high temperatures, comprising a metal hydride of the type that releases large quantities of gas when heated above a threshold temperature that is higher than those to which said environment is subject; electrical heating means primarily for said hydride; an electrically conductive diaphragm of metal capable of withstanding said threshold temperature; a housing capable of withstanding said threshold temperature and divided by said diaphragm into two sealed airtight chambers, namely a transducer chamber containing said hydride and the gas emitted therefrom and an anti'transducer chamber; a first electrical circuit connected to said diaphragm and having a first contact member capable of withstanding said threshold temperature in said transducer chamber, against which said diaphragm normally rests and away from which it is movable under pressure; and a second electrical circuit connected to said diaphragm and having a second contact member in said anti-transducer chamber against which said diaphragm is movable under pressure and which is normally not in contact with said diaphragm, said contact members when apart from said diaphragm being insulated from said diaphragm by high temperature ceramic, whereby said diaphragm and said contact members act as switches actuated by gas released from said hydride.

7. An electrical relay capable of use in an environment subject to high temperatures comprising a metal hydride of the type that releases large quantities of gas when heated to a threshold temperature above the temperatures to which said environment is subject; electrical heating means primarily for sai dhydride; a plurality of electrically conductive diaphragms of metal capable of withstanding said threshold temperature; a high-temperature resistant housing divided by said diaphragms into three scaled airtight chambers, namely, a transducer chamber containing said hydride and the gas emitted therefrom and two anti-transducer chambers; and a pair of electrical circuits each connected to one said diaphragm and having a contact member in said anti-transducer chamber of that diaphragm against which said diaphragm is movable under pressure, said contact members being insulated from said diaphragms except when they are in contact, by high temperature ceramic, whereby said diaphragms and said contact members act as switches actuated by gas released from said hydride.

8. An electrical relay capable of operating in environments subject to high ambient temperatures comprising an electrically conductive diaphragm of metal substantially unaffected by said high temperatures; a heat-resistant housing divided by said diaphragm into first and second sealed airtight chambers; a transducing agent in each said chamber comprising a metal hydride of the typ: that releases large quantities of gas when heated above a threshold temperature that is higher than the highest of said ambient temperatures; separate electrical heating means for said agent in each said chamber; and a pair of electrical circuits connected to said diaphragm, cach having a high-tr:mperature-resistant contact member, one contact member being in each said chamber, against which said diaphragm is movable when the pressure in the opposite chamber is the higher, ceramic insulation means normally insulating said contact members from said diaphragm, whereby said diaphragm and said contact members act as a single-pole doublethrow balance-type switch.

9. An electrical relay capable of great miniaturization and of operation and use in environments subject to high temperatures, comprising an insulating center member of insulating high-temperature ceramic material having conduit means joining its opposite sides; first and second closure members of high-temperature ceramic insulating material sealed to each said side, said first member having an electrically conductive contact member of hightemperatitre-resistant metal spaced from said center member; an electrically conductive diaphragm of high-temperature-resistant metal between said center member and said first closure member, dividing the space between them into two sealed airtight chambers; a heating element on the opposite side of said center member from said diaphragm; a metal hydride of the type that releases large quantities of gas when heated above a tbeshold temperature above the highest temperature to which the environment is subject, covering said heating element, both said hydride and said element being sealed between said center member and said second closure means; and an electrical circuit with one sid: connected to said diaphragm and the other side to said contact member, against which said diaphragm is movable under pressure, whereby said diaphragm and said contact member act as a switch actuated by gas released from said hydride.

19. The relay of claim 9 wherein said high-temperature-resistant metal is chosen from the group consisting of molybdenum, tungsten, and platinum, and the highmclting-point alloys of each of them.

11. An electrical relay capable of miniaturization and of operation in high-temperature environments, comprising a high-temperature ceramic insulating center plate having a flat side and a recessed side and opening means between said sides; a high-temperature ceramic cover plate sealed to each said side, the one on said recessed side having an electrically conductive button; an electrically conductive diaphragm of high-melting-point metal between said center plate and the cover plate on said recesscd side, dividing the space between them into two scaled airtight chambers; a flat resistive high-melting point coating on said flat side providing a heating element; a fiat coating of a metallic hydride of the type that releases large quantities of gas when heated above a threshold tcmperature that is higher than the temperature of said environment, on top of said resistive coating, said coatings being between said center plate and the cover plate for the flat side; and an electrical circuit with one side connected to said diaphragm and the other side to said button, against which said diaphragm is movable under pressure, whereby said diaphragm and said button act as a switch actuated by gas released from said hydride.

12. An electrical relay capable of operation at a predetermined high temperature, comprising an imperforate enclosure of high-temperature-resistant material; a charge of hydrogen gas in said enclosure; a metallic hydride in said enclosure of the type that takes up hydrogen when heated in a range above said predetermined high temperature and thereby substantially decreases the pressure within said enclosure; electrical means for heating said hydride; an electrically conductive portion of said enclosure that is movable in response to pressure changes in said enclosure; and an electrical circuit connected to said portion and having contact means adjacent said portion against which said portion is movable to close said circuit at high internal pressures and away from which said portion moves when said hydride is heated to a predetermined temperature.

13. An electrical relay for use in environments where ambient temperatures are high, comprising a metal hydride of the type that takes up large quantities of gas when heated in a range above said high ambient temperatures and releases it when recooled to a temperature still above said ambient temperatures; electrical heating means for said hydride; an electrically conductive molybdenum diaphragm; a molybdenum housing divided by said diaphragm into two sealed airtight chambers, namely, a transducer chamber containing said hydride and the hydrogen gas emitted therefrom and taken up into it and an anti-transducer chamber; a charge of hydrogen gas in said transducer chamber and an electrical circuit connected to said diaphragm and having a molybdenum contact member in said anti-transducer chamber, said diaphragm normally being against said contact member but being movable away from it when the pressure in said transducer chamber drops, whereby said diaphragm and said contact member act as a switch actuated by gas released from or taken up by said hydride.

14. The relay of claim 13 wherein said anti-transducer chamber is pressurized to cause actuation of said switch at a predetermined pressure value in said transducer chamber.

15. An electrical relay comprising a metal hydride that takes up large quantities of gas when heated and releases it when cooled; electrical heating means for said hydride; an electrically conductive diaphragm of a metal that retains its strength and springiness well at high temperatures and which does not then react with hydrogen to a deleterious degree; a housing of high-heat-resistant material divided by said diaphragm into two sealed airtight chambers, namely, a transducer chamber containing said hydride and the hydrogen associated therewith, a charge of hydrogen gas in said transducer chamber; and an anti-transducer chamber; and an electrical circuit connected to said diaphragm and having a contact member of high-heat-resistant material also resistant to hydrogen in said transducer chamber, against which said diaphragm is movable when the pressure in said transducer chamber drops, said diaphragm moving away therefrom when the pressure in the transducer chamber rises, whereby said diaphragm and said contact member act as a switch actuated by gas released from said hydride.

16. The system of claim 15 wherein said anti-transducer chamber is pressurized to cause actuation of said switch at a predetermined pressure value in said transducer chamber.

17. An electrical relay comprising an insulating center member of ceramic insulating material having conduit means joining its opposite sides; first and second ceramic closure members sealed to each said side, said first member having an electrically conductive contact member spaced from said center member; an electrically conductive diaphragm between said center member and said first closure member, dividing the space between them into two sealed airtight chambers, a heating element on the opposite side of said center member from said diaphragm; a metal that forms hydride by taking up large quantities of hydrogen when heated and releasing it when cooled, covering said heating element, both said hydride-forming metal and said element and an excess of hydrogen being sealed between said center member and said second closure means; and an electrical circuit with one side connected to said diaphragm and the other side to said contact member, against which said diaphragm normally rests but away from which it is movable when the pressure drops due to the hydride-forming metal taking up gas, whereby said diaphragm and said contact member act as a switch actuated by gas taken up by and released from said hydride.

18. An electrical relay comprising a hydride from the group consisting of zirconium, titanium, vanadium, niobium, tantalum, and palladium; electrical heating means for said hydride; a high-temperature-metal snap-action diaphragm having a generally spherical active area; a high-temperature-resistant metal housing divided by said diaphragm into two sealed airtight chambers, namely, a transducer chamber containing said hydride and the gas emitted therefrom and an anti-transducer chamber; an electrical circuit connected to said diaphragm and having a high-temperature-resistant metal contact member in said anti-transducer chamber, against which said diaphragm is movable under pressure, whereby said diaphragm and said contact member acts as a switch actuated by gas released from said hydride, said contact member being barely closer to said diaphragm than said housing so that the 13 14 terminal surfaces of said housing and said diaphragm FOREIGN PATENTS closest to said diaphragm are nearly coplanar to provide 11,393 5/1913 Great Britain a substantially planar support for said diaphragm when said diaphragm is actuated by flattening its spherical ac- OTHER REFERENCES I tive area; and ceramic means insulating said contact mcm- 5 Glbb, y Journal Of Chfimlcfll bcr from Said housing ucation, vol. 25, October 1948, pp. 577-582.

Grunewald: General Chemistry of the Hydrides, Fair- References the Examiner Corp. Div.), June 2,

UNITED STATES PATENTS 10 1948' 2 271 307 1942 Ray BERNARD A- GILHEANY, Primary Examiner. 2,381,582 8/1945 Erickson 2()083 S. B. SMITH, JR., H. M. FLECK, JR.,

2,697,766 12/1954 Goldmuntz 200-122 Assistant Examiners. 

1. AN ELECTRICAL RELAY SUITABLE FOR USE IN ENVIRONMENTS SUBJECTED TO HIGH TEMPERATURES COMPRISING A HIGH-TEMPERATURE-RESISTANT ENCLOSURE; METALLIC HYDRIDE IN SAID ENCLOSURE HAVING A THRESHOLD TEMPERATURE ABOVE THE TEMPERATURES TO WHICH THE ENVIRONMENT IS SUBJECT; ELECTRICAL MEANS IN HEAT CONDUCTING RELATIONSHIP WITH SAID HYDRIDE FOR PRIMARILY HEATING SAID HYDRIDE ABOVE SAID THRESHOLD TEMPERATURE; A SNAP-ACTION ELECTRICALLY CONDUCTIVE DIAPHRAGM OF METAL WHOSE ABILITY TO SNAP-ACT IS NOT GREATLY AFFECTED BY HIGH TEMPERATURE CLOSING AN AREA OF SAID ENCLOSURE AND DEFLECTED BY VARIATION IN PRESSURE; AND AN ELECTRICAL CONTACT IN SAID ENCLOSURE OF HIGH-TEMPERATURE-RESISTANT METAL AGAINST WHICH SAID DIAPHRAGM IS SNAPPED UNDER SOME PRESSURE CONDITIONS AND AWAY FROM WHICH IT IS MOVED UNDER OTHER PRESSURE CONDITIONS. 